Convincing evidence for macroevolution exists, which is why I do not berate evolutionists for their beliefs. If I were agnostic and listening to an erudite evolutionist, I might say, “Thou hast almost convinced me to become an evolutionist.” One example of impressive evidence for evolution across life forms is the discovery of Tiktaalik. Tik…taa…who? Tiktaalik is a northern native Canadian name for freshwater fish. This creature supposedly lived 365 million years ago. Its discovery in 2004 created quite a stir, not so much for its fossilized structure, but for the manner in which it was discovered. More than a decade ago, Edward Daeschler, Neil Shubin, and Jennifer Clack decided that the best place to look for an elusive transitional fossil bridging the divide between fish and tetrapods was in Nunavut in northern Canada. This region, although now in the Arctic Circle, was once thought to be near the equator and to have a warm climate. So in 1999 they sent research teams to Ellesmere Island (77° 3'37.23"N; 88° 5'52.40"W) to look for transitional fossils in an area where an intermediate animal would most likely be found.

After 5 years of digging with little success, the researchers discovered what they had been looking for: a fossilized fish-tetrapod looking animal. The animal had characteristics similar to a fish but with skeletal characteristics akin to a crocodile. Its skeletal structure enabled it to support itself on land and water, and the presence of spiracles (small holes) on its flat head suggests that the animal had primitive lungs, in addition to gills.

The researchers’ hypothesis was confirmed. It is an amazing discovery. Notwithstanding the impressiveness of this discovery, it does not rise to the level of what we might call definitive scientific evidence because it was not a crucial test of macroevolution. What is a crucial test? Let’s consider a brief example from Relativity. When Einstein introduced his theories of Special Relativity and Relativity in the early 1900s, his ideas created a stir. Back then Newton was still revered as the undisputed champion of science and the thought of anyone challenging Newton’s ideas was considered heretical. However Einstein boldly challenged Newton’s ideas. He argued that space and time are not constant as Newton had supposed; rather space and time differed based on one’s state (hence the name “relativity”).

Searching for ways to test Einstein’s theory, scientists decided to study the light from stars next to a fully eclipsed sun. If Einstein was right then the sun’s gravity well would cause the light from ‘nearby’ stars to bend and thus appear shifted in the dark sky. And so in 1919 a British research team headed by Sir Arthur Eddington went on a distant journey to view a solar eclipse on Principe Island near the coast of Guinea in West Africa.

It was cloudy during the days leading up to the eclipse and a heavy thunderstorm rolled through the team's location on the morning of the much anticipated event (May 29th). The research expedition was in jeopardy of failing, nevertheless Eddington and his team set up their instruments and hoped for a miracle. Minutes before the eclipse when the sky was still overcast, anxieties grew as the moon moved in front of the sun and the sky darkened. Then suddenly, before the eclipse reached totality, the clouds parted revealing the corona of the sun and surrounding stars. The team quickly snapped their photos.

The photos revealed that light from ‘nearby’ stars (in the Hyades star cluster) had indeed shifted, as Einstein predicted. The sun’s gravitational pull shifted the position of the stars an average distance of 1.6 arcseconds. Like Tiktaalik, it was an amazing discovery.The Crux of the Matter Tiktaalik’s discovery provides reasonable evidence for accepting macroevolution, and Eddington’s eclipse study provides reasonable evidence for accepting Relativity, but the quality of evidence from these two studies are not on par. The essential difference is that one was a crucial experiment and the other was not.

A crucial experiment is one where a “do or die” scenario is set up that allows us to tentatively decide on the truth or falsity of a theory. Relativity was subjected to a do or die test and it survived. The bending of starlight around the eclipsed sun allowed us to ascertain with a great deal of certainty that Einstein was right. If the light had not bent, we would have had good reason to conclude that Einstein was wrong and we might still be going with Newton’s theory.

Tiktaalik, although an important and impressive discovery, was not a crucial test of macroevolution. By this I mean that Tiktaalik did not create a situation where the theory of macroevolution was subjected to a “do or die” scenario. If the Ellesmere research team had never discovered Tiktaalik then the theory of macroevolution would not have been any worse off. Explanations would have included, “Well, we’re not looking in the right place,” or “We just have to keep looking.”

The quality of scientific evidence hinges, among other things, on the possibility of finding something false. Scientific theories that have been repeatedly subjected to crucial tests and survived have earned the status of being proven beyond a reasonable doubt. Those that have not been subjected to crucial tests, like macroevolution, have not been proven beyond a reasonable doubt. This suggests that people can reasonably reject macroevolutionary explanations for the origins of humanity.

Although I think that your characterization of the evidential weight that may be given to this single archaeological finding is accurate, I also believe that you may be overgeneralizing when you claim that evolutionary theory has not been subjected to "crucial tests" and is therefore credibly deniable. My reading of your post is that with the term “crucial tests” you are referring to the problem of induction, identified by Karl Popper, which states that any number of confirming observations cannot prove a theory according to deductive logic (i.e. no matter how many transitional species fossils are discovered, evolutionary theory cannot be proven merely by evidence that supports it). Instead, Karl Popper proposed that a scientific theory must be falsifiable, or capable of being disproven by the observation of conceivable evidence in order to be scientific.

The fact that we can conceive of evidence which would falsify evolutionary theory (J.B.S. Haldane famously suggested that rabbit or mammalian fossils dated to the Precambrian geologic era would constitute evidence that would falsify a theory of gradual evolution which produces increasingly complex life forms from simpler ones) is why Karl Popper eventually conceded that evolutionary theory was capable of making falsifiable predictions and therefore a scientific theory. When you think about evolution in this way, as a scientific theory that makes falsifiable hypotheses about when in earth's geologic history one should observe life forms of increasing complexity (i.e. mammals are much more complex than the single celled bacteria and Ediacaran biota that flourished prior to the Cambrian Explosion of more complex life forms), then "crucial tests" of evolutionary theory are going on all the time. Richard Dawkins, the preeminent evolutionary biologist, has himself stated that discovering mammalian fossils in Precambrian rock formations would "blow evolution out of the water." The fact that archaeological expeditions of all geologic eras have not found such anachronistic fossils, but instead a gradual progression of increasing complexity in life forms over millions of years suggests that evolutionary theory has and continues to be subjected to what you term "crucial tests." Therefore, to suggest that doubting evolutionary theory is scientifically justifiable is an irresponsible mischaracterization of the philosophy of science.

Reply

Dave C.

1/30/2014 06:22:07 am

Julian,
Thank you for your detailed reply. You have a good grasp of theoretical issues, but I question your conclusion of an "irresponsible mischaracterization of the philosophy of science."

I think most would agree that there is a difference between noting that there are no mammalian fossils in precambrian dirt and checking for bending of starlight during an eclipse.

The absence of mammalian fossils in precambrian dirt is not a crucial test of evolution. It is an inductive inference from the best evidence. It is as much a crucial test of evolution as watching footballs at the Superbowl fly back down to earth is a crucial test of gravity. We see it all the time and there is no reason to suspect that the future will be any different from the past.

Now if evolutionists constructed an experiment testing whether natural selection acting on random mutations in the genome leads to a new life form, that would be a crucial test. If such a test were successful, all hail macroevolution! If such a test failed, macroevolution would be in danger of being tossed into the dustbin of failed theories like luminiferous ether and phlogiston.